Electrical condenser



Oct. 4, 1932. J. A. PROCTOR ELECTRICAL CONDENSER Filed Sept. 3, 19 sSheeis-Sheet 1,

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DI EMML INVENTOR Oct. 4, 1932. J. A. PROCTOR ELECTRICAL CONDENSER FiledSept. 3, 1925 3 Sheets-Sheet 2 INVENTOR \fQ/YA W aofof ATTOR N EY 1932-J. A. PROCTOR ELECTRICAL CONDENSER Filed Sept. 5, 1925 3 Sheets-Sheet 3INVENTOR \jflA/ 91. BEE? PFocToQ ATTORNEY Patented Oct. 4, 1932 UNITEDSTATES PATENT OFFICE JOHN ALBERT .PIROCTOR, OF LEXINGTON, MASSACHUSETTS,ASSIGNOR, BY MESNE AS- SIGNMENTS, T GENERAL ELECTRIC COMPANY, A COR-PCBATION OF NEW YORK ELECTRICAL CONDEI'JSER Application filed September 3,1925. Serial No. 54,190.

This invention relates to electrical condensers, particularly of thesheet type.

The object of the invention is to produce, and the production of, acondenser which is efiicient, sturdy and attractive, of constantcapacity, and capable of being manufactured readily and at low cost, tosell at low price, being suitable for use, for example, in radioreceiving sets. The invention consists of the improvements in vstructureand manufacturing disclosed hereinafter in connection with theaccompanying drawings, of which:

Fig. 1 is an exploded view illustrating partial assembly of thecondenser;

Fig. 2 is a diagrammatic elevation illustrating a further step in themanufacture;

Fig. 3 is a petspective, somewhat exploded, illustrating a further stepin the process; Fig. 4 is a section of the condenser shown in Fi 5,taken along the line 4-4, illustrating t e final step in themanufacture, and showing the completed structure, the height of thecondenser, however, being greatly exag erated for clearness;

1 of Fig. 4 showing the lateral projection of the terminals of the twoconnection plates;

Fig. 6 is a perspective of the complete condenser of Figs. 4 and 5; a

Fig. 7 is a central section of a modification resembling the condenserof Figs. 4-6 but lacking foil armatures;

Fig. 8 is a perspective illustrating a condenser having a stack likethat of Fig. 6 or that of Fig. 7 but having a modified form of clampingplates;

' Fig. 9 is a pers ective illustrating a condenser like that 0 Fig. 8but having a further modified form of clamping plates; In addition tothe desirable features of at tractiveness and of superficial areasufiicient for desired markings, an important desideratum of condensersof this type is the ability to have the capacity maintained constant andat the same time a low manufacturing cost. To these ends, the inventioncomprises a clamping construction by which the capacity is maintainedconstant, and the construction is adapted to continuous building up ig.5 is a plan of the completed condenser from the bottom upward, so thatthere is no need of interrupting the process to place an element beneathanother element which already has been assembled, the labor cost, bythis feature, being kept down to the minimum consistent with the sturdyand attractive properties of the device. at?

As illustrated in Fig. 4, the structure comprises two metal end clampingplates B and which hold the condenser stack between them and themselvesare held in clamping position as by a central metal rivet, such as theeyelet A; This figure is about double scale, and in addition it is to beunderstood that the thickness is greatly exaggerated for clearness, theactual thickness of the condenser being usuall less than one-quarter ofan inch, this type 0 condenser being particularly adapted for lowcapacities.

All the plates of conducting and dielectric .material, including endclamping plates B and U, are perforated, as shown, to allow their beingplaced around the central stud or rivet A which finally clamps togetherall the elements of the stack and prevents turnin of theconnectionplates Q, S, to be describe Each foil sheet is formed with twoperforations thru which stud A passes.

The construction is commenced, as indicated in Fig. 1, by setting rivetA vertically, with its lower end headed and its upper end unheaded. Thenlower perforated metal clamping plate B is laid down over and aroundrivet A. Thena few sheets of mica (or one thick mica) C (perforatedcentrally) are laid down over and around rivet A to 1n-' sulate themetal clamp plate B from the stack which now is to be built upwardlyaround rivet A. Insulator C, when used as preferred, preferably spacesthe condenser stack from metal clamp so that the latter is isolated fromthe electrostatic action in the stack. The stack is then built up bylaying all the rest of the perforated sheets and plates down over andaround rivet A.

The two condenser terminals, which project laterall beyond the stack andare of any desired con guration, are shown at W, X, in Figs. 5 and 6.They lie, preferably, not at opposite ends of the stack, but, as shownin 100 Fig. 4:, both above the top of the stack and adjacent one anothersave for a sheet of mica R between them. This location of the twocondenser terminals-W, X which are integral respectively with the twoterminal plates or connection plates Q, S, (Figs. 1, 3 and permits theexecution of the method hereinafter described in detail, wherein theassembly is effected continuously from the bottom upward without anyinterruption, as has been usual, to insert an element below afteranother element had been assembled on top.

The two terminals W, X, of Figs. 5 and 6 are tabs which project from(and preferably as shown are integral portions of) the two thin butstiff metal connection plates Q, and S lying on top (at one end) of thestack, as

shown in Fig. 4, and between one end of the.

stack and clamp plate B. This construction of stiff projecting tabterminals W, X which are integral with the connection plates Q, S,avoids all fragile foil connections to the terminals, particularly in aform like that of Figs. 4-6, where the condenser armatures consist oflead foil sheets.

As shown in Figsrl and 2, after the assembly of rivet A, bottom clampingplate B and insulating sheet C, the stack is built up of alternatingsheets of mica (dielectric) and foil armatures; and as shown at the topof Fig. 1, after the stack of perforated micas and foil armatures hasbeen completed, the lower connection plate Q is placed, via its centralperforation Q, down over and around rivet A. As shown in Fig. 1, thealternate foils are arranged to project from opposite sides of thestack, and each foil is provided with two perforations, as shown, andthe foils are much longer than the width of the stack, for a purposenowto be described. At this stage, the stud A extends thru only one ofthe perforations in each foil-sheet, i. e.,-the right-hand 7 holes inthe left-hand foils (Fig. 1), and the left-hand holes in the right-handfoils.

As shown in Fig. 2, after lower connection plate Q is assembled on thetop end of the stack, the projecting ends of the long lefthand foils areturned up vertically and then brought down horizontally on connectionplate Q around stud A, the left-hand holes D of these left-hand foilsbeing entered by stud V. Thereupon, as shown in Fig. 3, an upperinsulating sheet T (like lower insulating sheet C of Fig. 1), centrallyperforated, is laid down on said folded down foils around rivet A,permissively on adjacent the folded down foils as shown; and then theupper metal connection plate S is laid down around the rivet,permissively in cont-act with insulating sheet R. At this stage, theends of the long righthand foils (Fig. 3) yet projgect out beyond thestack. Then, as shown in ig. 4., the righthand projecting ends of thelong righthand foils, as previously the long lefthand foils, are broughtup to the left top of the foils on vertically, and then to the left anddown horizontally, so that they contact Wltll the surface of upperconnection plate S, the holes D2 in the foils (Fig. 1) being entered bystud V. Then the uppermost insulating sheet T (like lower sheets C andR) is laid on S. Then upper metal end clamping plate U, centrallyperforated, 1S laid down on said sheet T around rivet A; and finally theupper head V of the rivet is upset to clamp the entire st ucture asdesired. The holes in the folds -over ends of the foils space andthereby insulate them from metal stud A.

The capacity of such a condenser as that shown in Figs. 1-6 may be about2 micromicro-farads, this being the form constructed with the foils asabove described. For condensers of similar structure but of lowercapacity (say 250 micro-micro-farads), the form of Fig. 7 may be used,wherein no foils are employed, but where the armatures of oppositepotential are the connection plates Q, S, themselves, separated from oneanother by their mica dielectric R, and insulated from the end clampingplates B, U by mica insulators C and T, as before.

All the mica sheets may be about inch long. All the mica sheetdielectrics between the foil armatures may be 7 inch wide. The endinsulating micas C and T may be inch square. The mica R between the twoconnection plates Q and S in Figs. 4-6 may 106% inch long and inch wide.The foils are narrow enough to provide the insulating margins of micashown at M1, Fig. 3. The foils are long enough to permit the foldingback between clamps B and U, as shown in Fig. 4. j

The end clamping plates B and U are not connected in the circuit, beingelectrically connected together by compression stud or rivet I andinsulated from the condenser stack itself and connection plates Q and Sby means of insulating sheets C and T.

The location of both connection plates Q and S at the top of the stack(Figs. 1-6) in connection with the operations of folding the projectingfoils over and upon said connection plates, respectively, permits thecontinuous building up illustrated, i. e., from bottom to topcontinuously without interruption as heretofore to insert an elementbelow after another element or elements have been first assembled above.

The clamping by the plates B and U, when rivet A is upset, serves notonly to maintain constant the capacity of the condenser, but also toinitiate and maintain good contact between the respective two foilbunches and tWO connection plates Q, S. -As illustrated in Figs. 2-4:,all the projecting foils of each polarity are grouped together in abunch on top of their respective connection plates. Clamps B and U alsohold connection plates Q and S and their projecting integral tabs W andX from turning to undesired angular positions in the stack relative tothe mica insulator C, R and T and the mica-dielectrics between thearmatures. Also clamps B and U hold the foils in the positions in whichthey are assembled so asto preserve the insulation spacing from stud Awhich is provided by the foil holes.

In the form shown in Fig. 7, without foils as armatures, for lowercapacities, the two connection plates Q, and S are located midway Q,

between the clamping plates B and U, being separated from one another bymica dielectric sheet R; and each connection plate is insulated by micainsulating sheets from the adjacent end faces of the metal clampingplates.

The assembly process of Fig. 7 is the same as in Figs. 1-6, save onlyfor the laying of the foils in the latter and bending them up over anddown upon the connection plates around stud A.

If the superficial dimensions of clamping plates Band U are sufficientlysmall, and they are of steel or thick enough not to bend up at theiredges, the central rivet A will hold the structure under constantpressure to maintain constant capacity and the desired other clampingfunctions. In any event, the operation of upsetting the upper end ofrivet A is such as to put the condenser stack under the desiredmechanical pressure. Altho plates B and U may be of sheet metal, theyshould not be of such nature as to permit their periph eries to bendaway from the stack upon riveting at the center, to an extent sufficientto permit substantial loosening of the condenser elements. But theinvention involved in the stack itself may be employed in connectionwith any desired means of maintaining stack pressure, with any desiredform of plates B and U, separately or ointly, and any desired means forforcing them together.

Heretofore the manufacture of this general class of condensers hasincluded building of the condenser stack by girl operatives andtemporary clamping of the same by them to permit transport of theincomplete condensers to a more or less distant power machine whichapplied permanent clamps or clamping means, or both. This invention,however, is of such a nature that it permits an entirely differentsystem of factory production, i. e., it permits the entire completion ofthe condenser, including permanent. clamping, by the same girloperatives who build the stack, (or at least permits permanent clampingof the condenser without removing it from its assembly device), thisbeing advantageous in eliminating the step of temporary clamping andtransfer to a more or less distant finishing or riveting machine, (orfirst removing the condenser from its assembly device prior to suchtransfer), thereby reducing cost and insuring a ainst disassembly of thevarious elements 0 the condenser.

The stack of Fig. 4 is adapted for capacities up to .005 mfd; but abovethat capacity 1 the stack will have greater thickness. In order toassemble such a thicker stack in the same condenser, i. e., includinguse of foils having the same spaced holes, the above operations may bemodified as follows. Upon completion of the stack and before theapplication of the first or lower connection plate on its top end, thefirst group of project ing foils (at left, Fig. 2) may be folded overdirectly upon the stack. This permits the holes (Fig. 3, Fig. 1) thruthe projecting and folded portions of the foils to be centralized aroundeyelet A, notwithstanding the slight increase in stack thickness forhigher capacity. Then connection plate Q may be laid on top of suchfolded down foils and upon it insulating sheet B (Fig. 3). Then theother set of foils -.(right) is folded up, over, and down on Q,permitting centralizing of their holes around eyelet A, and on them thenis laid insulating separator T.

Figs. 6, 8 and 9 illustrate the large extent of superficial areaon theclamping plates, around central rivet A, which is available for desiredname-plate marking.

In Fig. 8, the modification of bottom clampingplate B consists of twointegral vertical extensions B1, between which fits upper clamping plateU. These extensions B1 serve torenclose those opposite sides of thestack from which the terminal connections W, X, do not project.

In Fig. 9, both clampin plates B and U are modified as in plate B ofFig. 8, plate U having sides U2, which abut sides B1 of plate B, toconstitute an enclosure of the opposite sides of the stack.

As shown in Figs. 6, 8 and 9, the end clamping plates, and articularlythat which is close to terminals l v, X (as the upper plate U when W andX are located at the top of the condenser stack) are formed with cutawayportions Y, in order to assist the top insulating pilate T in insulatingthe circuit terminals W, from the metal end clamping plates.

If desired, the operation of folding down the foils to the horizontalpositions shown at the left in Fig. 2 may be aided by any suitablemechanism, just as the operation of picking up, the foils from thehorizontal position shown at the right in Fig. 2 is effected by anysuitable mechanism. But it is usually sufficient to enlist the aid ofmechanism for picking up the foils from the horizontal position at theright of F ig. 2, and to leave the subsequent folding down of the foilsto the fingers i not difficult for the two bunches of foils to beengaged by the fingers of the operative to push them down and radiallytoward the central rivet or compression stud, and centralize them;because, as distinguished from the stacked foil-condition shown in Fig.2 where the foils lie flat on the assembly block and require to bepicked up, on the other hand in the picked-up foil-positions their endsare more or less free in the air in position to be folded down.

The eyelet rivet A, as a compression stud, may be a solid rivet; or aform of my condenser may be completed without the use of any rivetingmachine, when such compres sion stud consists of a bolt with a nut inplace of an upset rivet. ith such threaded form of central compressionstud, the capacity of the condenser can be adjusted by screwing up thenut.

Preferably, as shown in Figs. 1 and 3 (but not necessarily), theconnection plates Q and S, with their terminal tabs W and X, are locatedat right angles to the oblong foils, i. e., the tabs W and X projectfrom the sides of the stack from which the foils do not project. Anadvantage of this is that. (Fig. 3) the foils may be laid down with theaid of fixed guide pins projecting up through their per forations D2(and D3, Fig. 1) the projecting foils subsequently being lifted from offsuch guide pins to the more or less vertical positions which willfacilitate subsequent manual folding down of the foilson top of thecondenser stack. Such guide-pins of course facilitate centralizing thefoils and their perforations D1, D2 (Fig. 1) with reference to the studA. That is, the above-described relation between the tabs W and X andthe projecting foils of opposite polarity permits the perforated foilsbeing placed over the fixed guide pins and later lifted therefromwithout interference by tabs W, X; and also leaves the rest of thecondenser free, including tabs W and X, to be depressed in suitableapparatus if desired, in order to Q and S.

push the foils up from off such guide-pins.

In Figs. 8 and 9, the folds of the foils are covered by bent-over sidesof one or both of-the end clamping plates B and U, the other ends of thestack being exposed in order to permit the extension beyond the stack ofthe tabs W and X of the connection plates An alternative form ofcovering the folds of the foils is a metal plate just like flat clampingplate B of Fig. 1 but much thinner and shaped with bent-up sides likeplate B ofFig. 8, and lying on top of flat plate B of Fig. 1, the twobent-up sides of such thin plate extending, like the sides of B1 ofplate B of Fig. 8, to cover the folds of the foils.

The condenser hereof preferably is constructed entirely of metal andmica, it being unnecessary and not desirable to simple any of thevarious forms of artificially pro ufced insulating material for any ofthe elements of the condenser; the metal parts are the rivet orcompression stud A, the end clamping plates B and U and the twoconnection plates Q and S, and the foils when used, i. e. in the highercapacity forms; the mica parts are the dielectric sheets of thecondenser stack, and the insulating separators C, R and T. The endclamping plates B and U furnish all necessary stiffness, and extend overthe entire condenser stack, so that there is no need ,of employing thickinsulating sheets to impart stiffness to the stack. Also, by the construction shown, the end clamp plates B and U and compression stud A allare electrically independent of the stack, although mechanicallyconnected together; the foils (when used) being insulated from thecompression stud A by the spacings of their central perforations, andthe bottom and topmica separators C and T completely insulating the endclamping plates B and U from the condenser stack and from the connectionplates Q and S. On account of the fact that clamp plates B and U aremetallically connected together by stud A, they may be formed in onepiece, as

a flattened tube, the condenser stack with stud A being placed in thetube before complete flattening thereof, the tube then being flattenedand the stack compressed and the rivet head upset; or clamps B and U mayconstitute the two legs of a u clamp. But I prefer the two-part clampplates Band U as shown.

Connection plates Q and S are sufiiciently thicker than the foils(depending upon the material'of said plates) to be relatively rigid orstiff, that is sufficiently to be suitable for integral projectingterminals W; and X, which may be pe'rmissively flexible by the fingerswithout disadvantage. These plates Q and S may be, for example, of brassabout 1/64 inch thick, or of other metal of suitable thickness andstiffness to serve satisfactorily as terminals. These plates, beingthin, occupy little space in the length of the condenser between the endclamping plates B and U.

The holes Q1 and X1 in tabs W and X may serve for the reception ofsuitable circuit terminals; and these tabs W and X may be of any desiredconfiguration, extended beyond their free ends shown, and adapted tovarious kinds of terminals of the apparatus with which the condensersare to be used.

The word .mica as used in the claims is intended to mean preferablymica, but permissible to include substantially equivalent sheetinsulating material such as any of the artificially produced insulants.

I particularly point out and distinctly claim the part, improvement orcombination which I claim as my invention or discovery, as follows:

1. An electrical condenser of the sheet type, comprising a stack of micadielectr cs and two sets of foils of opposite polarity extendingsubstantially from opposite sides of the stack; two metal clampingplates over the ends of the stack but insulated therefrom; twosubstantially stiff metalconnection plates both located at one end ofthe stack near one clamping plate and insulated from one another andfrom said clamping plate and having terminal portions of desired shapeextending in opposite directions laterally beyond the stack between thetwo foil-sets; the micas, clamping plates and connection plates beingcentrally perforated; and a metal compression stud extending throughsaid perforations, spaced from the connection plates attheir-perforations, and contacting with the clamping plates, holdingthem at the desired mechanical compression; the foil portions in thecondenser stack and portions projecting therefrom each havingperforations substantially larger than the stud; and the two rojectingportions of the foil-sets respective y being folded into contact withthe respective connection plates, the edges of all said foilperforations surroundin but spaced from the stud; and the central olesthru the micas being smaller than the foil-holes.

2. An electrical condenser of the sheet type comprising a stack of micadielectrics and two sets of foils of opposite polarity extendingsubstantially from opposite sides of the stack; two metal end clampingplates; two substantially stiff metal connection plates both located atone end of the stack near one of the clamping plates and insulated, fromone another and from said clamping plate, the micas, clamping plates andconnection plates beingcentrally perforated; a metal compression studextending through said perforations and s aced from the connectionplates at their per orations; the foil portions in and projecting fromthe stack being perforated; and the .two projecting portions of the foilsets respectively being folded into contact with the respectiveconnection plates, the edges of their perforations being spaced from thecompression stud; the connection plates having portions extendinglaterally beyond the stack as terminals; and'the stack, folded foils andconnection plates being held under compression by the clamping platesand central compression stud.

3. An electrical condenser of the sheet type, comprisinga stack of mica:dielectrics and two sets-of foils of opposite polarity; two metal endclamping plates; two substantially stiff metal connection plates locatedbetween and insulated from the clamping plates and electricallyconnected'respectively to said foil sets, and having portions exspacedat the foil-holes from said compression stud and projecting from thestack and the projecting portions being perforated and folded intocontact with the respective connection plates; and the said connectionlates and folded foil portions of opposite polarity being held togetherin good contact, by the clariping plates and central compression stu 4.An electrical condenser of the sheet type, comprising two metal endclamping plates; two substantially stifi metal connection plates locatedbetween the clamping plates and having portions extending laterally asterminals beyond the clamping plates, all said parts being centrallyperforated; a metal compression stud extending through saidperforations; said connection plates being spaced from said central studat their perforations; said connection lates bein insulated from oneanother and rom the en clamping plates; and the clamping platesextending over the entire area of theend faces of the condenser.

5. An electrical condenser of the sheet sion stud means extendingthrough said perforations and engaging the clamping plates to hold thestack under mechanical compression.

6. An electrical condenser of the sheet type, comprising a stack'offoils and mica dielectrics all centrally perforated; a central metalcompression stud extending throu h said perforations, fitting in theholes in t e micas but of smaller diameter than the holes in the foils;metal end clamping plates extending over the end faces of the stack,centrally perforated and engaged by said stud; mica separators betweenthe clamping plates and the stack; and two substantially stiff metalconnection plates between the end of the stack and one clamping plate, amica separating plate being located between the two connection plates;the foils of opposite polarity projecting from opposite sides of thestack and adapted to be folded back in the space near the end clampingplate where the connection plates are located, the faces of such foldedfoils being in electrical contact with the respective connection plates.

7. An electrical condenser of the sheet type, comprising a thin stack ofarmature sheets and dielectric sheets, centrally perforated; metal endclamping plates also centrally perforated; a central metal compressionstud extending through the perfora said stack including foils ofopposite polarity projecting from opposite sides of the stack andadapted to be folded into the space between the end clamping plates; andconnection plates located adjacent but insulated from one another at oneend of the stack adjacent one clamping plate, and respectivelycontacting with the folded-over foils of opposite polarity respectively;said connection plates and foils .being insulated from said metal endclamping plates.

9. An electrical condenser of the. sheet type, comprising a condenserstack, metal end clamping plates extending over the end faces of thestack, insulated therefrom and clamping the same; two substantially'stifi metal connection plates located adjacent one another between oneclamping plate and the adjacent end of the stack; sai'd connectionplates being insulated from one another, con

nected respectively to the condenser ar1natures of opposite polarity andhaving integral portions extending laterally beyond the stack and endclamps, as condenser terr'ninals.

10,.An electrical condenser of the sheet type, comprisinga stack offoils and micas, metal end clamping plates extending over the ends ofthe stack, insulated therefrom and clamping the same; the stack-foils ofopposite polarity projecting laterally in bunches from the stack andadapted to be folded into the space between the end of the stack andoneof the two clamping plates; said folded foil hunches being insulatedfrom one another; and condenser terminals respectivelyconnected-with'said folded foils.

"11. An electrical condenser of the sheet type, comprising a stack offoils and micas, metal end clamping plates'extending over the end facesof the stack, insulated therefrom and clamping the same, the foils ofopp'osite polarity projectinfg laterally from the stack and adapted tobe olded into the space between the stack-end and one of said twoclamping plates; and two substantially stiff" metal connection plateslying also in said space and'respectively contacting with said foldedfoils, said connection plates having integral projections extendinglaterally from the stack at portions thereof from which the foils do notproject.

i 12. In an electrical condenser of the sheet stack type, theimprovement which includes a 'stiif metal connection plate locatedmechanically parallel with the stack-sheets and extending across the endof the stack stiffening the latter from side to side, and a stackarmature sheet projecting laterally from the stack and folded overmechanically parallel with said connection plate and into electricalsurstud extending through said stack and clamping plates and contactingwith the latter to hold the structure under mechanical compression; theedges of the perforations in said armature sheets being spaced from saidmetal stud, and insulating plates being interposed between said stackand clamping plates, causing said insulation of the clamping plates fromthe stack.

14. An electrical condenser of the sheet type, which comprises acentrally perforated condenser stack; metal end clamping platesextending over the end faces of the stack and insulated from the stack;condenser terminals; and a metaleyelet rivet extending thru thestack-perforation and engaging the end clamping plates to compress thestack; the armatures of the stack being insulated from said metal rivet.

15, An electrical condenser of tlie sheet type, which comprises acompression stud having an integral annular retaining flange, acentrally-perforated metal end clamp plate strung thereovcr and held bysaid flange; a stack of centrally perforated condenser elements alsostrung on said stud and against said clamp plate; a secondcentrally-per- 1 forated clamp plate also strung on said stud other inlateral relations wherein the perforations of the sheets are in registryand wherein at least one foil of one polarity projects a substantialdistance outside of the stack laterally beyond the adjacent dielectricsheet; and subsequently bending up said projecting portion of said foiland then folding it over the top end of the completed foilstaek in aposition for terminal contact, with- .in the superficial area of thestack-end, hetween said relatively fragile folded over foil and arelatively stiff connection plate.

17 In an electrical condenser of the sheetstack type, the improvementwhich includes two flat metal connection plates arranged face to facebut insulated from one another by a fiat insulating plate, said threeplates having substantially the same superficial dimensions as thestack-sheets and all lying face to face with one end of the stack andmechanically constituting a portion thereof; an armature sheet of onepolarity projecting laterally out from the stack and extending back intothe stack into face contact with one of said metal connection platestherein; and an armature of opposite polarity projecting laterally outfrom the stack and.

extending back into the stack into face con:

tact with the other of said metal connection plates therein whereby thetwo connection plates are connected, within the mechanical limits of thestack, to the opposite-potential stack-armatures; said connection plateshaving integral portions projecting laterally from the stack as exteriorcondenser terminals; all whereby the condenser can be built continuouslyfrom end to end and the armatures are relieved from duty as exteriorcondenser terminals.

18. In an electrical condenser of the sheetstack type, the improvementwhich includes two flat metal connection plates arranged face to facebut insulated from one another by a flat insulating plate, said threeplates being centrally perforated and strung on a central compressionstud; a condenser stack having its dielectric sheets centrallyperforated and strung on said stud face to face wvith one of saidconnection plates and forming one mechanical stack with said threeperforated plates; the individual armature sheets of the stack havingperforations thru their respective ends and occupied by said stud butthe stud being spaced from said armatures; an armature sheet of onepolarity having a perforated endprojecting laterally out from the stackand extending back into the stack into face contact with one of saidmetal connection plates therein, said stud there passing thru theperforation in said end; and an armature sheet of opposite polarityhaving a perforated end projecting laterally out from the stack andextending back into the stack into face contact with the other of saidmetal connection plates therein; said stud there passing thru theperforation in said end; and said connection plates having integralportions projecting laterally from the stack as exterior condenserterminals.

19. In an electrical condenser of the sheetstack type, the improvementwhich includes a metal connection plate located mechanically parallelwith the stack-sheets and extending across an end of the stack; astack-arma ture sheet projecting laterally out from the stack andextending back into face contact with said connection plate; a metalclamp plate located on the other end of the stack,

all said parts being centrally perforated; a compression stud extendingthru the perforations of said parts and holding the stack andcompression plates together; and an insulating plate located betweensaid connectionplate and the adjacent end of said stud.

20. In an electrical condenser of the sheetstack type, the improvementwhich includes two fiat metal plates stifi'er than other conductingelements in said stack spaced apart in the stack by a flat insulatingsheet of substantially the same superficial dimensions; said metalplates having integral portions projecting laterally from the stack asexternal condenser terminals.

21. In an electrical condenser of the sheetstack type, the improvementwhichincludes two centrally perforated flat metal plates spaced apart inthe stack by a centrally perforated fiat dielectric sheet ofsubstantially the same superficial dimensions; said metal stack, meansinsulating said clamping means from the stack, metal terminal plates forthe stack which are stiffer and heavier than the stack armatures,projecting beyond the edge of Said clamping means and held in position 81,es1,1so

thereby, the stack armatures having the projecting end portions bent tocontact with the terminal plates.

23. The combination with a capacitor stack 5 comprising sheets of foiland insulating material, of metallic clamping means for the stackcomprising metal end plates extending across the stack in bothdirections, means iI1- sulating said clamping means from the stack, 10metal terminal plates for the stack which are stifier and heavier thanthe foil and thinner and less stifi than said end plates, said terminalplates projecting beyond the edge of the clamping means and held inposition 15 thereby, and said foils having projecting end portions bentfor contact with said terminal plates.

JOHN A: PROCTORB

